Using Aliases in Multisite
Let’s say you have site 1, site 1a, site 1b, and so on set up on your server. You would like to have an alias for site 1b that only site 1b can get you then it needs to be set up under site 1b site folder. If you want a link that all sites share then you will need to do it under the root site, site 1. This will be called default under the alias settings in the product. These rules apply to all manual alias and automatic aliases.